Refactor DocSignedNotification for better encapsulation

Refactored `DocSignedNotification` to remove inheritance from
`EnvelopeReceiverDto` and introduced a required `EnvelopeReceiver`
property. Updated all usages across the codebase to align with the
new structure, including controllers, handlers, and tests.

- Improved encapsulation and reduced coupling by making
  dependencies explicit.
- Updated `AnnotationController`, `DocStatusHandler`,
  `HistoryHandler`, and `SendSignedMailHandler` to use the
  `EnvelopeReceiver` property.
- Adjusted `DocSignedNotificationTests` to reflect the new
  instantiation pattern.
- Updated XML documentation and ensured consistent access to
  `EnvelopeReceiver` properties like `EnvelopeId`, `ReceiverId`,
  and `EmailAddress`.

EnvelopeGenerator.API/Controllers/AnnotationController.cs

@@ -75,7 +75,7 @@ public class AnnotationController : ControllerBase
 
         var envelopeReceiverDto = await _mediator.ReadEnvelopeReceiverAsync(uuid, signature, cancel);
         var docSignedNotification = envelopeReceiverDto is not null
-            ? new DocSignedNotification(envelopeReceiverDto) { PsPdfKitAnnotation = psPdfKitAnnotation }
+            ? new DocSignedNotification { EnvelopeReceiver = envelopeReceiverDto, PsPdfKitAnnotation = psPdfKitAnnotation }
             : throw new NotFoundException("Envelope receiver is not found.");
 
         try
@@ -86,8 +86,8 @@ public class AnnotationController : ControllerBase
         {
             await _mediator.Publish(new RemoveSignatureNotification()
             {
-                EnvelopeId = docSignedNotification.EnvelopeId,
-                ReceiverId = docSignedNotification.ReceiverId
+                EnvelopeId = docSignedNotification.EnvelopeReceiver.EnvelopeId,
+                ReceiverId = docSignedNotification.EnvelopeReceiver.ReceiverId
             }, cancel);
             throw;
         }

EnvelopeGenerator.Application/Common/Notifications/DocSigned/DocSignedNotification.cs

@@ -16,25 +16,29 @@ namespace EnvelopeGenerator.Application.Common.Notifications.DocSigned;
 public record PsPdfKitAnnotation(ExpandoObject Instant, IEnumerable<AnnotationCreateDto> Structured);
 
 /// <summary>
-/// 
+/// Notification raised when a document is signed by a receiver.
 /// </summary>
-/// <param name="Original"></param>
-public record DocSignedNotification(EnvelopeReceiverDto Original) : EnvelopeReceiverDto(Original), INotification, ISendMailNotification
+public record DocSignedNotification : INotification, ISendMailNotification
 {
     /// <summary>
-    /// 
+    /// The envelope receiver information.
+    /// </summary>
+    public required EnvelopeReceiverDto EnvelopeReceiver { get; init; }
+
+    /// <summary>
+    /// The PSPDFKit annotation data.
     /// </summary>
     public PsPdfKitAnnotation? PsPdfKitAnnotation { get; init; }
 
     /// <summary>
-    /// 
+    /// Gets the email template type.
     /// </summary>
     public EmailTemplateType TemplateType => EmailTemplateType.DocumentSigned;
 
     /// <summary>
-    /// 
+    /// Gets the email address of the receiver.
     /// </summary>
-    public string EmailAddress => Receiver?.EmailAddress
+    public string EmailAddress => EnvelopeReceiver.Receiver?.EmailAddress
         ?? throw new InvalidOperationException($"Receiver is null." +
             $"DocSignedNotification:\n{this.ToJson(Format.Json.ForDiagnostics)}");
 }

EnvelopeGenerator.Application/Common/Notifications/DocSigned/Handlers/DocStatusHandler.cs

@@ -31,8 +31,8 @@ public class DocStatusHandler : INotificationHandler<DocSignedNotification>
     /// <returns></returns>
     public Task Handle(DocSignedNotification notification, CancellationToken cancel) => _sender.Send(new CreateDocStatusCommand()
     {
-        EnvelopeId = notification.EnvelopeId,
-        ReceiverId = notification.ReceiverId,
+        EnvelopeId = notification.EnvelopeReceiver.EnvelopeId,
+        ReceiverId = notification.EnvelopeReceiver.ReceiverId,
         Value = notification.PsPdfKitAnnotation is PsPdfKitAnnotation annot
                     ? JsonSerializer.Serialize(annot.Instant, Format.Json.ForAnnotations)
                     : BlankAnnotationJson

EnvelopeGenerator.Application/Common/Notifications/DocSigned/Handlers/HistoryHandler.cs

@@ -29,13 +29,13 @@ public class HistoryHandler : INotificationHandler<DocSignedNotification>
     /// <returns></returns>
     public async Task Handle(DocSignedNotification notification, CancellationToken cancel)
     {
-        if (notification.Receiver is null)
+        if (notification.EnvelopeReceiver.Receiver is null)
             throw new InvalidOperationException($"Receiver information is missing in the notification. DocSignedNotification:\n {notification.ToJson(Format.Json.ForDiagnostics)}");
 
         await _sender.Send(new CreateHistoryCommand()
         {
-            EnvelopeId = notification.EnvelopeId,
-            UserReference = notification.Receiver.EmailAddress,
+            EnvelopeId = notification.EnvelopeReceiver.EnvelopeId,
+            UserReference = notification.EnvelopeReceiver.Receiver.EmailAddress,
             Status = EnvelopeStatus.DocumentSigned,
         }, cancel);
     }

EnvelopeGenerator.Application/Common/Notifications/DocSigned/Handlers/SendSignedMailHandler.cs

@@ -31,7 +31,7 @@ public class SendSignedMailHandler : SendMailHandler<DocSignedNotification>
     protected override void ConfigureEmailOut(DocSignedNotification notification, EmailOut emailOut)
     {
         emailOut.ReferenceString = notification.EmailAddress;
-        emailOut.ReferenceId = notification.ReceiverId;
+        emailOut.ReferenceId = notification.EnvelopeReceiver.ReceiverId;
     }
 
     /// <summary>
@@ -42,11 +42,11 @@ public class SendSignedMailHandler : SendMailHandler<DocSignedNotification>
     {
         var placeHolders = new Dictionary<string, string>()
         {
-            { "[NAME_RECEIVER]", notification.Name ?? string.Empty },
-            { "[DOCUMENT_TITLE]", notification.Envelope?.Title ?? string.Empty },
+            { "[NAME_RECEIVER]", notification.EnvelopeReceiver.Name ?? string.Empty },
+            { "[DOCUMENT_TITLE]", notification.EnvelopeReceiver.Envelope?.Title ?? string.Empty },
         };
 
-        if (notification.Envelope.IsReadAndConfirm())
+        if (notification.EnvelopeReceiver.Envelope.IsReadAndConfirm())
         {
             placeHolders["[SIGNATURE_TYPE]"] = "Lesen und bestätigen";
             placeHolders["[DOCUMENT_PROCESS]"] = string.Empty;

EnvelopeGenerator.Tests/Application/DocSignedNotificationTests.cs

@@ -53,7 +53,7 @@ public class DocSignedNotificationTests : TestBase
 
         var annots = Services.GetRequiredService<PsPdfKitAnnotation>();
 
-        var docSignedNtf = new DocSignedNotification(envRcvDto) { PsPdfKitAnnotation = annots };
+        var docSignedNtf = new DocSignedNotification { EnvelopeReceiver = envRcvDto, PsPdfKitAnnotation = annots };
 
         var sendSignedMailHandler = Host.Services.GetRequiredService<SendSignedMailHandler>();
 

EnvelopeGenerator.Web/Controllers/AnnotationController.cs

@@ -72,7 +72,7 @@ public class AnnotationController : ControllerBase
 
         var envelopeReceiverDto = await _mediator.ReadEnvelopeReceiverAsync(uuid, signature, cancel);
         var docSignedNotification = envelopeReceiverDto is not null
-            ? new DocSignedNotification(envelopeReceiverDto) { PsPdfKitAnnotation = psPdfKitAnnotation }
+            ? new DocSignedNotification { EnvelopeReceiver = envelopeReceiverDto, PsPdfKitAnnotation = psPdfKitAnnotation }
             : throw new NotFoundException("Envelope receiver is not found.");
 
         try
@@ -83,8 +83,8 @@ public class AnnotationController : ControllerBase
         {
             await _mediator.Publish(new RemoveSignatureNotification()
             {
-                EnvelopeId = docSignedNotification.EnvelopeId,
-                ReceiverId = docSignedNotification.ReceiverId
+                EnvelopeId = docSignedNotification.EnvelopeReceiver.EnvelopeId,
+                ReceiverId = docSignedNotification.EnvelopeReceiver.ReceiverId
             }, cancel);
             throw;
         }